Leaky gut and intestinal mucosal injury among dogs with clinically subclassified atopic dermatitis

We aimed to determine the relationships between intestinal mucosal injury (based on diamine oxidase [DAO] concentrations), physiological modulators of intercellular tight junctions, and leaky gut biomarkers (based on zonulin concentrations) in dogs with atopic dermatitis. We previously demonstrated that gut restoration alleviates canine atopic dermatitis (CaD) based on the interaction between the gut microbiome and dermatological diseases, which is referred to as the "gut-skin axis." However, we observed the reverse in this study. This short-term, open-label, non-repeated study involved 30 owned dogs with CaD. Their CaD was clinically subclassified based on their Canine Atopic Dermatitis Extent and Severity Index version 4 (CADESI-04) scoring based on proposed benchmarks for mild (10), moderate (35), and severe (≥60) AD skin lesions]. Clinical interpretation and laboratory examination were composed of epidermal corneometric analytes (epidermal hydration and pH), CADESI-04 scores, and intestinal biomarkers. The DAO concentrations for the mild (≤10; Group I), moderate (≥11-35; Group II), and severe (≥60-180; Group III) groups were 2.1-6, 0.9-5.2, and 0.4-4.1 ng/mL, respectively. The data on the decline in DAO concentrations with disease progression were valuable (p = 0.031). The zonulin concentrations (ng/mL) for Groups I, II, and III were 14.67 ± 2.45, 13.40 ± 4.56, and 10.89 ± 6.49, respectively (p = 0.008). Their epidermal hydration levels for Groups I, II, and III (59.90 ± 17.77, 30.75 ± 14.59, and 17.58 ± 11.71, respectively) were statistically significant. However, their pH values for Groups I, II, and III (5.02 ± 0.64, 4.47 ± 0.35, and 4.66 ± 1.07, respectively) were not. This study highlights the exploration of the gut-brain-skin axis and leaky gut.